Dizziness Vertigo HINTS Exam

Dizziness Vertigo HINTS Exam

Highlights

  • In patients who present to the ED with a primary complaint of dizziness, vertigo or imbalance, stroke is a rare cause (0.7%)[1] and most do not benefit from a HINTS exam.
  • In dizzy patients who are found to have acute vestibular syndrome (AVS- acute onset continuous vertigo with nausea/vomiting, nystagmus and gait instability), stroke is much more likely, perhaps 15-35% per an estimate by Newman-Toker[2] and HINTS is indicated.
  • The HINTS exam has been shown to reliably distinguish between stroke and vestibular neuritis in patients with AVS, when performed by neurologists (96.5% sensitivity for central vertigo) and outperforms early MRI (41-85%) but has not been well studied among emergency physicians.
  • Edlow assets that emergency physicians can learn the HINTS exam with practice and time but should add two additional safeguards (gait testing and a focused neurologic exam) to safely exclude a central cause of acute vestibular syndrome[3].
  • A patient shared decision making discussion is reasonable when considering discharge of a patient with acute vestibular syndrome due to the lack of evidence about emergency physicians proficiency with the HINTS exam and the higher risk of central vertigo in this population.  
  • An alternative approach in acute vestibular syndrome, if you are not comfortable with the HINTS exam, is a neurology consultation, since early MRI is not reliable enough to exclude CVA and CT is essentially useless (except in the setting of hemorrhage, tumor or dissection)[4].

Clinical scenario

  • The second-year resident presents a case to you of a 35-year-old male who presents to the ED complaining of sudden onset of continuous vertigo and difficulty walking. 
  • The patient’s neurologic exam is completely normal except for horizontal nystagmus.
  • He reports some subjective imbalance while walking but the resident observed him walking without assistance.  
  • The resident recalls that the HINTS exam is less reliable when performed by emergency phsicians and wonders if you recommend that she order an MRI for the patient in the morning?

When should the HINTS exam be performed?

  • The majority of patients who present with dizziness will not benefit from a HINTS exam.
  • According to the review of dizziness by Edlow3, the HINTS exam is only intended for patients with continuous dizziness (in contrast to episodic dizziness), who also have nystagmus. 
  • HINTS should not be performed if the patient does not have nystagmus or if the patient’s dizziness is not continuous.

Why is the HINTS exam useful?

  • Except for rare causes such as barotrauma, toxins (anticonvulsants, SSRIs, anticholinergics, loop diuretics) and Wernicke’s syndrome, the crucial differential for emergency physicians evaluating continuous vertigo is between vestibular neuritis and stroke. 
  • According to Edlow[5] and Kattah[6], the HINTS exam, performed in patients with nystagmus, can distinguish between vestibular neuritis and stroke.[7]
  • HINTS outperformed MRI during the initial 48 hours after onset of continuous vertigo with nystagmus and gait disturbance, with a HINTS exam sensitivity of 96.5% compared to MRI sensitivity of 85% for large strokes[8] and a sensitivity of 41% for small strokes[9].

Is HINTS reliable when performed by emergency physicians?

  • Two recent studies have informed our knowledge about the accuracy of the HINTS exam when performed by emergency physicians. 
  • The first was a 2020 systematic review of 5 prior studies[10], totaling 617 patients, evaluating patients with acute continuous vertigo.  The HINTS exam, when performed by neurologists, had a sensitivity of 96.7% and a specificity of 94.8% for identifying central vertigo (stroke, 35+/-17%, peripheral vertigo 30+/-16%%, hemorrhage 2%). 
  • Only one study in the systematic review included emergency physicians and these were fellowship trained in vascular neurology.  Their use of HINTS resulted in a lower sensitivity (83%) and specificity (44%) for central vertigo. The study gave us no evidence on how emergency physicians without fellowship training perform the HINTS exam.
  • A 2021 retrospective study[11] reviewed whether HINTS was used appropriately in ED patients presenting with a primary complaint of dizziness or vertigo. 
  • Nearly 20% of dizzy patients received all or part of the HINTS exam but most of the patients (96.9%) did not meet criteria for receiving the test, most often because the patients lacked nystagmus or continuous vertigo.
  • Final conclusions: we don’t yet have good evidence on whether emergency physicians, even with fellowship training, can accurately perform the HINTS exam.
  • Emergency physicians perform HINTS inappropriately in dizzy patients who do not meet the narrow parameters of acute vestibular syndrome.

Can emergency physicians use a normal HINTS exam to safely discharge a patient with AVS?

  • UpToDate’s review of vertigo, in the section entitled “Brain Imaging”, states that a younger patient with acute sustained vertigo, with no other neurologic signs or symptoms, and with nystagmus and an examination that is consistent with peripheral vertigo does not need immediate MRI if there is improvement within 48 hours.
  • However, neuroimaging is indicated if the examination is not entirely consistent with a peripheral lesion, if there are prominent risk factors for stroke, if there are neurologic signs or symptoms, if the patient cannot walk or if there is a new headache accompanying the vertigo (dissection?).
  • Edlow asserts that “with time and practice, physicians can learn to perform and interpret these tests”. 
  • He recommends adding two additional safeguards to the traditional three part ocular HINTS exam: 1) a focused neurologic exam, and 2) ability to sit and walk unassisted.  
  • Here are Edlow’s 5 questions for acute-onset continuous dizziness.
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  • This is the focused neurologic exam that Edlow recommends:
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How do I perform the HINTS exam?

3 part ocular HINTS Exam in pictures[12]
1. Horizontal head impulse testing (Head Impulse)

  • Hold the patient’s head, allowing their mandible to rest and relax into your palms. Ask the patient to fixate on an object (ie, your nose). Then, quickly and gently move the patient’s head to the left or right and then back to the neutral position again.
  • Central Finding: Absence of saccade (no large beats of nystagmus as the eyes “catch up” to re-fixate on examiner’s nose) is concerning.
Head Impulse Test

2. Direction-changing nystagmus in eccentric gaze (Nystagmus)

  • Assess for a presence of nystagmus.
  • Central Finding: Any vertical nystagmus or horizontal nystagmus that changes direction with lateral gaze (“bidirectional nystagmus”) is concerning.
Nystagmus Test

3. Vertical skew (Test of Skew)

  • Have patient look at your nose and then cover one eye for several seconds and then uncover that eye quickly.
  • Central Finding: Realigning of the eye vertically is concerning.
  • Caveat: This response may fatigue over serial exams during a short time period.
Direction-changing nystagmus

Dizziness algorithm

  • This algorithm is primarily from a AAFP review article[13] but incorporates Edlow’s[14] 5 question expanded HINTS exam that includes gait testing and a focused neurologic exam.
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Case Scenario Wrap-Up

  • You perform the HINTS exam with the resident.
  • There was no central nystagmus (vertical, torsional or bidirectional), no skew, and the patient had an abnormal head impulse test consistent with peripheral vertigo.
  • The focused neurologic exam and gait testing were normal.
  • After a shared decision making conversation, the patient acknowledged understanding of the knowledge gap regarding HINTS exam, declined admission for neurology consult and MRI, and opted instead for treatment with a 10 day steroid taper for vestibular neuritis and two day follow-up with PCP.

[1] Kerber, KA et al. Stroke among patients with dizziness, vertigo and imbalance in the emergency department: a population-based study. Stroke. 2006; 37:2484-2487.

[2] http://nanosweb.org/files/4_N-Tacutevestib_syndrome.pdf

[3] Edlow, J. Diagnosing Patients With Acute-Onset Persistent Dizziness. Annals of Emergency Medicine. 2018; 71(5):625-631.

[4] Edlow, J. Diagnosing Patients With Acute-Onset Persistent Dizziness. Annals of Emergency Medicine. 2018; 71(5):625-631.

[5] Edlow JA, Newman-Toker. Using the physical examination to diagnose patients with acute dizziness and vertigo. J Emerg Med. 2016;50:617-628.

[6] Kattah JC et al. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive the early MRI diffusion-weighted imaging. Stroke. 2009; 40:3504-3510.

[7] Vanni, S et al. Can emergency physicians accurately and reliably assess acute vertigo in the emergency department? Emerg Med Australas. 2015;27:126-131.

[8] Newman-Toker, DE et al. HINTS outperforms ABCD2 to screen for stroke in acute continuous vertigo with dizziness. Acad Emerg Med 2013 Oct; 20(10):986-96.

[9] Saber Tehrani AS, Katttah JC et al. Small strokes causing severe vertigo: frequency of false-negative MRIs and nonlacunar mechanisms.  Neurology. 2014;83:169-173.

[10] Ohle, R et al. Can Emergency Physicians Accurately Rule Out a Central Cause of Vertigo Using the HINTS Examination? A Systematic Review and Metaanalysis.  Acad Emerg Med. 2020 Sep; 27(9):887-896.

[11] Dmitriew, C. Diagnostic Accuracy of the HINTS Exam in an Emergency Department: A Retrospective Chart Review. 2021 Apr; 28(4):387-393.

[12] https://www.emra.org/emresident/article/hints-exam/

[13] Muncie HL. Dizziness: Approach to evaluation and management. 2017 Feb: 95(3):154-162.

[14] Edlow, J. Diagnosing Patients With Acute-Onset Persistent Dizziness. Annals of Emergency Medicine. 2018; 71(5):625-631.